With an increase in capacity of information processing in recent years, various information recording technologies have been developed. In particular, the surface recording density of an HDD using magnetic recording technology is continuously increasing at an annual rate of approximately 100%. In recent years, an information recording capacity exceeding 200 gigabytes/platter with a 2.5-inch diameter of a magnetic disk for use in an HDD or the like has been desired. To fulfill such demands, an information recording density exceeding 400 gigabits/inch square is desired to be achieved.
To achieve high recording density in a magnetic disk for use in an HDD or the like, a magnetic disk of a perpendicular magnetic recording type (a perpendicular magnetic recording disk) has been suggested in recent years. In an in-plane magnetic recording type, an easy axis of magnetization of a magnetic recording layer is oriented in a plane direction of a base surface. In the perpendicular magnetic recording type, the easy axis of magnetization is adjusted so as to be oriented in a perpendicular direction with respect to the base surface. Compared with the in-plane magnetic recording type, the perpendicular magnetic recording type can suppress a thermal fluctuation phenomenon more, and therefore is suitable for increasing recording density.
Furthermore, as technologies that improve recording density and resistance to thermal fluctuation, suggested are magnetic recording media, including a discrete track medium preventing interference of an adjacent recording track by patterning a non-magnetic track in parallel between magnetic tracks for recording, and a medium called a bit pattern medium with arbitrary patterns artificially regularly arranged.
For the magnetic recording medium, such as the discrete track medium and the bit pattern medium described above, suggested are a technology of forming a magnetically-separated magnetic pattern by, after forming a magnetic recording layer on a non-magnetic base, partially implanting ions for non-magnetization or amorphousness (Patent Document 1) and a technology of forming a magnetic pattern by, after forming a magnetic recording layer on a non-magnetic base, partially milling the magnetic recording layer to form asperities and physically separating the magnetic recording layer (for example, Patent Document 2).
Specifically, first, a resist film is formed on a magnetic recording layer, and a stamper having a desired asperity pattern formed thereon is imprinted on the resist to transfer the asperity pattern. Alternatively, a photoresist film is formed on a magnetic recording layer, and a desired asperity pattern is formed on the photoresist by photolithography. Then, ions are implanted in the magnetic recording layer via the formed recessed part, or the magnetic recording layer exposed on the surface of the recessed part is milled by etching, thereby separating the magnetic recording layer.
On the other hand, with an increase in density in the magnetic recording technology, a magnetic head is being changed from a thin-film head to a magneto-resistive head (an MR head) and a giant magneto-resistive head (a GMR head). The floating amount from the base of the magnetic head is narrowed to approximately 5 nm.
With a low floating amount of the magnetic head, the magnetic head may collide with a magnetic disk when use to damage the surface of the magnetic disk. Therefore, the magnetic head is desired to have a high floating stability.
For example, Patent Document 3 discloses a discrete track medium with a magnetic recording part divided at a non-recording part. Also disclosed therein is a structure in which a surface of the magnetic recording part is formed as being convex and a surface of the non-recording part is formed as being concave. According to Patent Document 3, a stable floating characteristic can be obtained.